Lubricating oil



Patented Sept. 5, 1939 STATES PATENT QFFICE LUBRIOATING 01L No Drawing.

Application September 15, 1937,

Serial No. 163,916

'7 Claims.

This invention relates to the treatment of hydrocarbonoils .and, moreparticularly to the incorporation in hydrocarbon lubricating oils ofcertain compounds which have the efiect of im- .5 proving the physicalcharacteristics and lubricating properties of the oils.

Hydrocarbon lubricating oils have a tendency to deteriorate uponstanding for a reasonable length of time under ordinary storageconditions. This tendency becomes greatly exaggerated under conditionsof use, particularly where the oil is maintained at an elevatedtemperature for a considerable period of time. For instance, when usedfor lubricating internal combustion engines, such as employed in modernautomobiles and aeroplanes where the oil is in contact with therapidlymoving and highly heated engine parts,

this deterioration becomes pronounced and results in serious changes inthe composition and 20 characteristics of the oil.

One of the consequences of this deterioration is the formation in theoil of a heavy sludge which collects after a time in the oil pump andoil lines of the engine, eventually clogging them to 5 such an extent asto prevent or greatly impair the efiicient lubrication of the engine.This sludge-like material also becomes deposited on the pistons of theengine and frequently causes sticking of the piston rings and valves ofthe enso gine.

This deterioration further causes an increase in the viscosity of thelubricating oil, thereby putting a correspondingly increased load on theengine. Such increase in the viscosity over that ordinarily selected forthe conditions of use is particularly objectionable, for example, whenstarting the motor in cold weather.

It has also been found desirable to lower the pour point of hydrocarbonlubricating oils. Such lubricating oils frequentlyhave pour points inthe neighborhood of 20 F. or even considerably higher, and the viscosityat low temperatures of such oils used as a lubricant is particularlyobjectionable when starting an internal combustion engine in coldweather.

Extensive research has been carried out in developing lubricating oilswhich are stable under conditions of storage and use and which have apour point as low as possible. led to the addition to lubricating oilsof certain materials thought to have a stabilizing influence on the-oilsby retarding the above-mentioned deterioration. VA Other materials havebeen added to these oils to lower the pour point thereof. 55' Myinvention provides a new type of compound This work has' to be added tolubricating oils or the like whereby the objectionable deterioration ofthe oilis materially diminished, the viscosity and other physicalcharacteristics of the oils areimproved, and the pour point of the oilis advantageously 5 lowered. My invention also provides an improvedlubricating oil in which the rate of sludge or gum formation ismaterially decreased and which has a substantially lowered pour point.

The formation of sludge in ordinary lubricat-, ing oils and the increasein viscosity under the conditions of use are generally recognizedphenomena. The extent to which these phenomena occur, under uniformconditions, varies with the particular lubricating oil used, and therate at which they proceed in a particular oil generally increases asthe temperature increases.

Special methods have been devised for measuring the rate ofsludge-formation in various oils and under various temperatureconditions. A generally satisfactory method has been described in theAmerican Society of Testing Materials Proceedings, vol. 24, page 967whereby the time is determined in which 10 milligrams of sludge isformed in 10 grams of the oil maintained at a 95 definite temperaturewhile air is bubbled through the oil at a specified rate. This timeisdesignated sludging time 'and is a measure of the rate ofsludge-formation in that particular oil under the particular conditionsof the test. The so term sludging time as used hereinafter refers to theabove-determined measure of the rate of sludge-formation and is arelative measure of the tendency of the oil to form sludge underconditions of storage or use.

I have discovered that'the sludging time of hydrocarbon lubricating oilsis greatly increased by the addition to the oil of a small proportion ofa compound derived from erucic acid. In addition to increasing thesludging time, these 40 derivatives of erucic acid have a general effectof raising the viscosity index of the oil and appreciably lowering thepour point of the oil. Metallic and aromatic derivatives of erucic acidhave been found to have these effects upon hydrocarbon iubricating oilswhen used in varying proportions. The metallic derivatives of erucicacid appear to be more effective, however, than the aromaticderivatives. Aluminum erucate, for example, has been found to beespecially efiective although alpha naphthyl erucate and benzyl erucatemay be used with particular advantage.

The derivatives of erucic acid used in accordance with my invention maybe prepared, for example, by forming the sodium salt of erucic acid andsubjecting the salt to the action or" a metallic salt capable of.precipitating the desired metallic derivative of erucic acid or to theaction of an aromatic compound, such as an alcohol, capable of reactingwith erucic acid to give the desired derivative. The erucic acid isreadily obtainable as the chief constituent of rapeseed oil.

In preparing a small quantity of the erucic acid,

I used a blown rapeseed oil which had an acid number of 7.05, asaponification number of 203.0, an iodine value of 61.1, and an A. P. I.gravity 'of 152. 3000 c. c. of this rapeseed oil were saponifled byadding thereto a solution comprising 540 grams of sodium hydroxidedissolved in about 3000 c. c. of water. After complete saponification ofthe oil the mixture was diluted with five times its own volume of waterand heated until all of the soap was in solution. A quantity of 36%hydrochloric acid was then added to the soap solution until no furtherprecipitation occurred. The mixture was allowed to settle for about onehour and the aqueous layer then drawn off. The remaining oil layer waswashed twice with water at a temperature of about 140 F. and the waterdrawn ofi after each of these washings. The oil layer which had beenwashed was dissolved in approximately threetimes its volume of 95% ethylalcohol. Upon chilling the solution to a temperature of about -5 to 0 C.and maintaining the solution at this temperature for about five to sixhours, crude erucic acid was precipitated from the solution. This crudeerucic acid was separated from the solution by filtering and was thenrecrystallized twice by dissolving it in two parts by weight of 95%alcohol and by chilling the solution to a temperature between ap--proximately -5 to 0 C. for each recrystallization. After recrystallizingthe acid for the third time by dissolving it in one part of warm 95%alcohol and allowing the acid to crystallize from the solution at roomtemperature, a further yield of erucic acidwas obtained from thefiltrate of this third recrystallization by chilling the filtrate to atemperature of about 5 to 0 C. After removing by evaporation the alcoholheld in the solid product separated during the three recrystallizationoperations together with that crystallized from the filtrate of thethird recrystallization, a total yield of 470 grams of erucic acid wasobtained.

Aluminum erucate was prepared from the erucic acid thus obtained byneutralizing 50 grams of the erucic acid with the theoretical quantityof sodium hydroxide in the form of 20 1%. solution. 400 c. c. of asolution made up the aqueous solution by decantation, the alu-' minumerucate was washed several times with water accompanied by decantationof the wash water from the solid product after each washing. Upon dryingthe'product on a hot plate a yield was obtained which amounted to of thetheoretical yield of aluminum erucate.

addition agent may comprise the substantially pure aluminum erucate to'which a relatively small proportionof free erucic acid has been added.The presence or absence, as the case may be, of the free erucic acid inthe addition agent had a distinct effect upon the modification of thephysical characteristics of the oil by the addition agent. 7

My invention will be further described with specific reference toaluminum erucate. It is to be understood, however, that the followingspecific examples are merely illustrative of my invention as applied toparticular oils and that my invention is not limited to the use ofaluminum erucate or the following specific proportions thereof. Tables Iand II show the effect of varying proportions of aluminum erucate on theviscosity, sludging time and pour point of a Pennsylvania motor oilhaving a gravity of 28.5,

a flash point of 430 F., and a viscosity index Table I Percent additionagent in blend 0 0.5 1. 0 1. 5 2. 0 3. 0

Vis. at F 413 414 430 433 457 1465 V15. at 210 F 59. 3 59. 8 61. 1 61. 964. 0 149. 7 i i. 100. 1 102. 4 103. 4 106. 6 108. 9 122 Sludging time 0tar) hours 58 60 62 72 77 102 Four, F 5 1o B-1o B-lO 13-10 13-10 TableII Percent addition agent in blend 0 0.5 1. 0 1. 5 2. 0 3. 0

Vis. at 100 F 413 415 421 425 424 456 Vis. at 210 F 59. 3 59. 9 60. 560. 7 60. 6 62. 7 100. 1 102. 6 103. 4 103. 5 103. 3 104. 1 Sludgingtime (0.1% tar) hours 58 23 64 82 84 Pour, F 5 0 15 15 -15 15 Aconsideration of the results shown in Tables I and II indicates that forthis particular Pennsylvania motor oil the sludging time of blends ofaluminum erucate in the oil is substantially independent of the amountof free erucic acid, up to at least 10%, in the addition agent. Thesludging time and viscosity index are both markedly increased by theaddition of the oil of 3% of aluminum erucate, regardless of the amountof free erucic acid, up to at least 10%, in the addition agent. The pourpoint of this Pennsylvania oil is lowered 15 to 20 F. by the addition ofaluminum erucate over a wide range of percentages of aluminum erucate inthe blend.

Tables III and 11] show the effect of adding aluminum erucate to ahydrocarbon lubricating oil having a gravity of 20.8, a vflash point of370 F.,

a.viscosity index of 23.4, and a pour point of F. The addition agentused in Table III is the same as that used in Table I, while theaddition agent used in Table IV is the same as that used in Table II.

Table III Percent addition agent in blend 0 0.5 1.0 1.5 2.0 3.0

Vis. at 100 F 502 510 519 54 551 1407 V15. at 210 F 53. 9 54. 0 54. 755. 7 56. 5 122. 4 V. I 23.4 21.3 26.3 31.9 34.9 112 Slud ing time (0.1percent tar hours 8. 5 9 17. 5 20. 5 21. 5 27. 5

Table IV Percent addition agent in blend 0 0.5 1.0 1.5 2.0 3.0

Vis. at 100 F 502 506 502 502 508 552 Vls. at 210 F 53. 9 53. 6 53. 553. 7 54. 3 56. 4 V. I 23. 4 17. 5 17. 8 24. 9 25. 9 32. 3 Sludging time(0.1 percent tar) hours. 8. 5 9. 5 14.0 21.0 18. 0 30 The results ofTables III and IV indicate that for a hydrocarbon lubricating oil havingthe foregoing physical characteristics the addition of aluminum erucateto the oil increases the sludging time of the oil substantiallyindependently of the amount of free erucic acid, up to at least 10%, inthe addition agent. The viscosity index of the oil is also increased bythe incorporation of aluminum erucate in the oil, this eifect being morepronounced in the blends containing 3% aluminum erucate.

The aluminum erucate used to produce the results shown in Tables Ithrough IV was prepared from an unblown rapeseed oil having asaponiflcation number of 178, an acid number of 1.13, and an iodinevalue of 100. The erucic acid was prepared from this rapeseed oil inaccordance with the method described by Noller and Talbot in OrganicSynthesis, vol. X, p. 44 (John Wiley 8; Sons, Inc.). The erucic acidthus obtained had a saponification number of 148, an acid number of 132,and an iodine value of 63.1. This erucic acid was dissolved in thetheoretical quantity of 20 B. aqueous sodium hydroxide solution,

and aluminum erucate was precipitated from this solution by addingthereto an aqueous solution of aluminumsulphate containing an excess ofaluminum sulphate over the theoretical quantity necessary for completeprecipitation. The solid aluminum erucate was separated from thesolution by filtration, and the solid product was washed with water andsubsequently dried.

The efiectiveness of aluminum erucate in lowering the pour point oflubricating oils is indicated in Table V which shows the results of theincorporation of small quantities of aluminum erucate in three distincttypes of hydrocarbon lubricating oils. Blank oil A has a gravity 0128.4, a flash point of 430 F., a viscosity of 431 seconds SayboltUniversal at 100 F., a viscosity index of 103.4, and a pour point of 5F. Blank 011 B has a gravity of 27.7, a flash point of 445 F., a.viscosity of 618 seconds Eraybolt Universal at 100 F., a viscosity indexof 103, and a pour point of 20 F. Blank oil C has a gravity of 26.4, aflash point of 395 F., a viscosity of 200 seconds Saybolt Universal at100 F., a viscosity index of 73.0, and a pour point of 10 F.

Table V Percent addition agent BlankA" BlankB" BlenkC" 5 20 B-l5 -l5 2013-15 15 10 B-15 From the above tabulation it is apparent that the pourpoint of blank oil A is reduced to a minimum by the addition of about0.5% aluminum erucate, that the pour point of blank oil B is reduced toa minimum by the addition of approximately 1.5% aluminum erucate, whilethe pour point of blank oil C is reduced to below 15 F. by theincorporation therein of 0.25% aluminum erucate.

It must be emphasized, however, that my invention is not to be limitedbythe proportions of the addition agent used in the foregoingillustrations. For example, it has been found that as little as 0.1% ofaluminum erucate has a salutary effect in lowering the pour point ofcertain hydrocarbon lubricating oils, while it has also been found thathigh percentages, that is, up to 10% of aluminum erucate has a favorableeffect in reducing the tendency of hydrocarbon lubricating oils to formsludge under conditions of use. When percentages in the neighborhood of5 to 10% of the addition agent are used, the addition agent may containwith advantage larger proportions than 10% of free erucic acid.

Thus, it will be seen from the foregoing tabulations that theincorporation in hydrocarbon lubricating oils of a small proportion ofaluminum erucate for example, increases the sludging time of the oil,increases, in most instances, the viscosity index of the oil, andgreatly reduces the pour point of the oil. The effectiveness of smallquantities of this addition agent together with the fact that it may bereadily prepared from a relatively inexpensive raw material imparts tothis addition agent, and the others hereinbefore enumerated, a low costand a high degree of efficiency.

I claim:

1. The method of inhibiting the formation of sludge in a hydrocarbonlubricating oil and of lowering the pour point thereof which comprisesincorporating in the oil between about 0.5 and 3.0% of a metallic saltof erucic acid.

2. The method of inhibiting the formation of sludge in a hydrocarbonlubricating oil and of lowering the pour point thereof which comprisesincorporating in the oil between about 0.5 and 3.0% of aluminum erucate.

3. The method of inhibiting the formation of sludge in a hydrocarbonlubricating oil and of lowering the pour point thereof which comprisesincorporating in the oil between about 0.5 and 3.0% of aluminum erucatecontaining a relatively small proportion of free erucic acid.

4. An improved lubricating -oil resistant to sludge formation and havinga reduced pour point which comprises a hydrocarbon lubricating oilcontaining between about 0.5 and 3.0% by weight of a metallic salt oferucic acid.

5. An improved lubricating oil resistant to sludge formation and havinga reduced pour point which comprises a hydrocarbon lubricating oilcontaining betweenabout 0.5 and 3.0% by weight of a metallic salt oferucic acid together with e refietively smaller proportion of free emoteacid.

6. An improved lubricating oil" resistant to sludge formation and havinga. reduced pour point which comprises a hydrocorbon lubncoting oilcontaining between about 0.5 and 3.0% by weight aluminum emcei'e.

7. An. improved lubricating oil resistant to sfiudge formation andhaving a reduced. pour point which comprises a, hydrocarbonlubricatfine; oil containing between about 0.5 and 3.0% olumnum erucatetogether with a relatively moller proportion of free erucic acid.

ROBERT C. C

